LYMPHOCYTOZOON COBAYsE 

 DESCRIPTION OF PLATE II. 



Fig. i. — A small extracellular amoeboid form of the parasite as it occurs in the 

 peritoneal fluid of guinea-pigs. Fig. io shows these to be amoeboid as seen in the blood 

 on the jelly : in fig. 1 1 one is stained by Giemsa's method. 



Figs. 2, 3. — The early included parasite found in the lymphocytes of the blood of 

 guinea-pigs — the dot stage. 



Development of the Female and Asexual Elements 



Fig. 4. — Two parasites included within a lymphocyte of the peritoneal fluid of a 

 guinea-pig— the chromatin dots have multiplied ; one shows the next phase to fig. 3 in the 

 formation of the female element, the other is an example of the rod formation (male 

 element). 



Figs. 5, 6, 7, 8. —Other examples of the intracellular development of the asexual and 

 female elements. The parasites grow and their chromatin dots increase in numbers. 



Fig. 9. — The newly freed parasite as it sometimes appears in the peritoneal fluid of 

 guinea-pigs ; occasionally it breaks away from its host-cell before its development is 

 complete. 



Figs. 10, 11. — The completely developed female and asexual elements. One is shown 

 with a pseudopodium protruded, as frequently seen by the jelly method. The only 

 apparent means of distinguishing between the female and asexual elements is to observe the 

 acts of conjugation. 



Development of the Male Element 



Fig. 12. —The chromatin dot in fig. 3 becomes elongated into a dumb-bell, which 

 splits longitudinally into two rods. 



Figs. 13, 14. 15. — -The chromatin rods multiply by. simple fission within the parasite 

 inclusion in the lymphocytes of the blood of guinea-pigs. 



Fig. 16. — Each rod develops a flagellum at each end. This figure shows one rod as 

 seen within the cell-inclusion highly magnified 



Fig. 17. — -A parasite in a lymphocyte of the blood of guinea-pigs. It contains many 

 rods and many fligella as seen stained by the jelly method. 



Fig. 18. — From a central point in each rod longitudinal splitting takes place both 

 ways along the length of the rod anil each flagellum, until there is a maze of threads 

 radiating from the central point wound up within the cell-inclusion. 



Fig. 19.— A parasitic inclusion prematurely burst on the jelly. The chromatin of the 

 microgametes (spirochetes) is stained ; the central chromatin hub and the spokes are 

 developed from the rod. 



Fig. 20. — The completely develope I gametes as seen just bef>re the cell-inclusion 

 (the microgametocyte) bursts ; the nucleus of the lymphocyte is squeezed into a corner of 

 the cell. From the blood of a guinea-pig. 



Fig. 21. — A maze of gametes just born from a burst parasite, but caught in a clot and 

 stained by the jelly method. 



Fig. 22. — The male elemsnts, the microgametes (spirochetes \ 



Development of the Conjugated Forms 



Fig. 23. — Conjugation between male and female elements. 



Fig. 24. — The chromatin of the conjugated form divides and subdivides, and the 

 parasite becomes included within a lymphocyte of the blood, peritoneal flaid, etc., of the 

 guinea-pig. 



Figs. 25, 26, 27, 28. — The growth of the conjugated parasite in the cytoplasm of the 

 lymphocyte; this phase consists of a sphere containing a great number of small chromatin 

 masses. 



Figs. 29, 30, 31, 32. — Budding. Each conjugated parasite gives off buds. Each bud 

 contains chromatin, and on the jelly the process of their separation can be watched. 

 Sometimes, as in fig. 32, the conjugated form buds within the host-cell and the buds can then 

 be seen embedded in the cytoplasm. Each bud resembles the free amoeboid forms as 

 shown in fig. 1. Thus the cycles of schizogony and sporogony are complete. All figures 

 are as seen on the jellies except fig. 11, which is stained by Giemsa's method. The pictures 

 are by Miss E. Barry, E. A. Ross, and J. W. Cropper. 



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